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Compact nuclear fusion reactor is 'very likely to work,' studies suggest

nytimes.com

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Re: Compact nuclear fusion reactor is 'very likely to work,' studies suggest

#31

Post by mtzaldo »

isoprophlex wrote: post #8

I never quite understood the math behind power densities in a fusion reactor. In the sun, isn't energy production occurring at something like 100-1000 W/m3? So, if you want to build a multiple MW fusion plant, shouldn't these plants be ridiculously huge compared to, say, a wind turbine rated at a couple of MW? Is the density of the plasma so much higher in a fusion reactor? Also, something else I never grokked, how d…

I recommend the book "5 Equations that changed the world", it gives you the idea how modern world works and how that is direct influence of math. For example how electricity is being generated using dynamos.

Re: Compact nuclear fusion reactor is 'very likely to work,' studies suggest

#33

Post by coldtea »

NikolaeVarius wrote: post #20
isoprophlex wrote: post #8

I never quite understood the math behind power densities in a fusion reactor. In the sun, isn't energy production occurring at something like 100-1000 W/m3? So, if you want to build a multiple MW fusion plant, shouldn't these plants be ridiculously huge compared to, say, a wind turbine rated at a couple of MW? Is the density of the plasma so much higher in a fusion reactor? Also, something else I never grokked, how d…

You boil water from the neutrons/heat it creates.

So in the end it's a glorified boiler!

Re: Compact nuclear fusion reactor is 'very likely to work,' studies suggest

#34

Post by wcarss »

eigenhombre wrote: post #5

Having read about tokamaks for thirty years, I'd be curious what specific breakthroughs and innovations have occurred since the 1980s, which lead to the optimism described in the article (which is otherwise frustratingly devoid of detail). It's great there are seven-peer reviewed articles about SPARC, but plasma was not my specialty in physics -- would any specialists care to comment on whether there is anything part…

My layman's understanding is that recently available (~last 5 years) industrial scale processes to produce rebco tape[1] is the specific advance in superconductor tech that's specifically enabling higher tesla magnetic field strengths from significantly smaller and lighter and easier to manage magnets, so you can get a system that's "powerful enough" to run net posititve at a size that's small enough to be built by a few universities rather than a few dozen nations (i.e. ITER), so the complexity of the engineering project drops from "unimaginable" to "just very high".

1 - https://www.fusionenergybase.com/concept/rebco-high-temperat...

2 - really great talk from a few years ago about this from MIT's Plasma Science Fusion Centre: https://www.youtube.com/watch?v=L0KuAx1COEk (really, if you like this stuff, give the talk a watch. It's great.)

Re: Compact nuclear fusion reactor is 'very likely to work,' studies suggest

#35

Post by alexpotato »

rsynnott wrote: post #27
isoprophlex wrote: post #8

I never quite understood the math behind power densities in a fusion reactor. In the sun, isn't energy production occurring at something like 100-1000 W/m3? So, if you want to build a multiple MW fusion plant, shouldn't these plants be ridiculously huge compared to, say, a wind turbine rated at a couple of MW? Is the density of the plasma so much higher in a fusion reactor? Also, something else I never grokked, how d…

The actual fusion in the sun happens in only a small part At the middle. The rest is just there to provide mass :) > Also, something else I never grokked, how do you get the power out? The plasma heats up, but how do you turn that into useful electrical energy? Steam turbines; same as fission or coal. Or gas turbines, if you want to get fancy.

There is a science fiction story by, I believe, Isaac Asimov which has as it's main story point that:

- fusion is developed

- b/c of fusion, the cheapest "rocket fuel" is basically water heated into steam by the fusion reactor

- people on Earth get upset about the "spacers" taking all of the "earthers" water

- the spacers then have to go to other sources of water in the solar system (I think it was either rings of Saturn or the asteroid belt)

The thing that struck me at the time was the "water as propellant" without the extra step of breaking H2O into hydrogen and oxygen.

Re: Compact nuclear fusion reactor is 'very likely to work,' studies suggest

#36

Post by rkaplan »

wcarss wrote: post #34
eigenhombre wrote: post #5

Having read about tokamaks for thirty years, I'd be curious what specific breakthroughs and innovations have occurred since the 1980s, which lead to the optimism described in the article (which is otherwise frustratingly devoid of detail). It's great there are seven-peer reviewed articles about SPARC, but plasma was not my specialty in physics -- would any specialists care to comment on whether there is anything part…

My layman's understanding is that recently available (~last 5 years) industrial scale processes to produce rebco tape[1] is the specific advance in superconductor tech that's specifically enabling higher tesla magnetic field strengths from significantly smaller and lighter and easier to manage magnets, so you can get a system that's "powerful enough" to run net posititve at a size that's small enough to be built by a…

This is the correct answer. A key reason Rebco is so much better than older alternatives is that it can be cooled to superconductivity using only liquid nitrogen (77K), as opposed to liquid helium, which is much harder to work with.

Re: Compact nuclear fusion reactor is 'very likely to work,' studies suggest

#38

Post by Florin_Andrei »

aaronblohowiak wrote: post #30
eigenhombre wrote: post #5

Having read about tokamaks for thirty years, I'd be curious what specific breakthroughs and innovations have occurred since the 1980s, which lead to the optimism described in the article (which is otherwise frustratingly devoid of detail). It's great there are seven-peer reviewed articles about SPARC, but plasma was not my specialty in physics -- would any specialists care to comment on whether there is anything part…

so you get the plasma spinning and you have two problems: containment and instability. better magnets and faster control systems are the two big things that (in my layman's-bad-at-physics understanding) have really advanced in the last decade.

The intense non-linearity of magnetic phenomena is a source of major issues here.

Why can't natural laws be more simple and linear? (joking, sure, but it does feel that way sometimes)

Re: Compact nuclear fusion reactor is 'very likely to work,' studies suggest

#39

Post by foobarian »

rkaplan wrote: post #36
wcarss wrote: post #34

Earlier quoted context omitted.

My layman's understanding is that recently available (~last 5 years) industrial scale processes to produce rebco tape[1] is the specific advance in superconductor tech that's specifically enabling higher tesla magnetic field strengths from significantly smaller and lighter and easier to manage magnets, so you can get a system that's "powerful enough" to run net posititve at a size that's small enough to be built by a…

This is the correct answer. A key reason Rebco is so much better than older alternatives is that it can be cooled to superconductivity using only liquid nitrogen (77K), as opposed to liquid helium, which is much harder to work with.

Nit: ultimately the new magnets need to be stronger for the same volume no matter how easy the cooling is to work with. That part is just a nice bonus.

Re: Compact nuclear fusion reactor is 'very likely to work,' studies suggest

#40

Post by Florin_Andrei »

mdorazio wrote: post #16

Here's the actual summary: "Although many significant challenges remain, the company said construction would be followed by testing and, if successful, building of a power plant that could use fusion energy to generate electricity, beginning in the next decade." In other words, "very likely" in this case means "if several roadblocks are overcome, it might be a net-positive power generator in a decade". Even so, this…

> this is still exciting given how anemic advancement in the fusion space has been for 50+ years

At the top of my list for when I'll be king for a day is - massive, national-scale investments (think: reaching towards one percent of GDP) in fusion research.

This is a major roadblock, but things look awesome on the other side. We just need to get our stuff together to hop over this fence somehow.

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